Electric motors for vehicles need to have high efficiency to conserve power. Furthermore, in unmanned aerial vehicles, light weight and compact electric motors are also desirable. Thus, ironless motors are often used which can provide the benefit of no iron losses due to changing flux direction.
Motors are normally rated for the peak power and efficiency of the motor. In some applications, high part load efficiency is desired, which is high efficiency when machine is loaded at a partial load, i.e. 15% or some other percent.
What is needed is a higher efficiency compact motor.